svn commit: r268087 - head/sys/kern

[Konstantin Belousov]

On Sun, Jul 06, 2014 at 11:39:00PM +0200, Mateusz Guzik wrote:
> On Sun, Jul 06, 2014 at 11:18:51PM +0200, Mateusz Guzik wrote:
> > On Tue, Jul 01, 2014 at 09:09:03PM +0300, Konstantin Belousov wrote:
> > > On Tue, Jul 01, 2014 at 02:54:10PM +0200, Mateusz Guzik wrote:
> > > > It is passed down to MAC (mac_vnode_execve_will_transition and
> > > > mac_vnode_execve_transition) and then vfs_mark_atime.
> > > And we can lock it only there.
> > > 
> > 
> > I don't see how this code could be reorganized to reduce vnode lock
> > coverage and not add unlock + lock pair to the common case (no hwpmc and
> > no credential change).
> > 
> > vfs_mark_atime is only called when execve cannot return an error
> > anymore, with vnode locked and proc unlocked. Moving it before hwpmc
> > checks would require additional pair of proc unlock/lock.
> > 
> > That said, I would prefer to just commit previously proposed fixup.
> > 
Ok.

> 
> hm, I only now notice that fexecve case does:
> vn_lock(binvp, LK_EXCLUSIVE | LK_RETRY)
> 
> I guess this can be safely changed to LK_SHARED.

No, it cannot.  The VV_TEXT flag must be handled under the exclusive lock.
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